Sheet separator

ABSTRACT

A sheet-separating apparatus is provided for use in conjunction with vacuum fingers for feeding sheets seriatim from a stack. The sheet separator comprises a plurality of stationary hollow tubes adjacent one end of a sheet support, each tube having an orifice in the form of a vertical slot facing the support. Air is supplied to each tube and is directed in a stream through the slot by an oscillating riffling finger associated with each tube and having a tab extending into the slot to vary the effective area thereof. When the riffling finger is in a lowered position against the top of the stack, air is forced through a small area of the slot at a high velocity to separate the edges of the upper sheets as a vacuum finger engages the uppermost sheet. As the riffling fingers move upwardly from the stack the effective area of each slot becomes larger, causing a gradual decrease in the velocity of the air and a gradual increase in volume. After the vacuum fingers have separated the uppermost sheet from the stack the riffling finger moves downwardly to grip the remaining sheets on the stack.

United States Patent [72] Inventor Hans 0. Stoever Rush, N.Y.

21 Appl. No. 40,028

[22] Filed May 25, 1970 [45] Patented Dec. 14, 1971 [73] Assignee Eastman Kodak Company Rochester, N.Y.

[54] SHEET SEPARATOR 10 Claims, 9 Drawing Figs.

Primary Examiner-Joseph Wegbreit Assistant Examiner-Bruce H. Stoner, Jr.

Attorneys-Robert W. Hampton and Gary D. Fields ABSTRACT: A sheet-separating apparatus is provided for use in conjunction with vacuum fingers for feeding sheets seriatim from a stack. The sheet separator comprises a plurality of stationary hollow tubes adjacent one end ofa sheet support. each tube having an orifice in the form of a vertical slot facing the support. Air is supplied to each tube and is directed in a stream through the slot by an oscillating riffling finger as sociated with each tube and having a tab extending into the slot to vary the effective area thereof. When the riffling finger is in a lowered position against the top of the stack, air is forced through a small area of the slot at a high velocity to separate the edges of the upper sheets as a vacuum finger engages the uppermost sheet. As the rifiling fingers move upwardly from the stack the effective area of each slot becomes larger, causing a gradual decrease in the velocity of the air and a gradual increase in volume. After the vacuum fingers have separated the uppermost sheet from the stack the riffling finger moves downwardly to grip the remaining sheets on the stack.

PATENTHJ [ED141371 SHEET 2 BF 2 HANS O. STOEVER INVENTOR.

ATTORNEYS SHEET SEPARATOR BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a sheet separator and more particularly to a separator which separates the sheets by means of variable air streams.

2. Description of the Prior Art In the printing art, copy sheets typically are fed seriatim from a supply, such as a stack of copy sheets, to a printing or transfer position where an image is placed on the copy sheets. These copy sheets are fed from the top of the stack by means of vacuum fingers which pick up the top sheet and feed it to a transfer means, such as feed rollers, which feed the sheet to a transfer station. A paper support for supporting the supply of paper is normally provided, having adjustable side guides for holding sheets of different selected width and length. To facilitate separation of the top sheet of paper from the stack by the vacuum finger, a riffling device can be provided of the type shown in U.S. Pat. No. 2,942,877, to Fowlie et al., entitled, Sheet Feed Mechanism for Duplicators." This device comprises a plurality of spaced reciprocal tubes adjacent the leading end of the stack which are connected respectively to a supply of forced air. The upper end of each tube is provided with a plurality of orifices facing a stack of sheets on a support and includes a rifiling finger or blade which is formed integrally with the tube and engages the top of the stack when the tube is in the lowered position. The reciprocal tubes move upwardly as vacuum feeding fingers move downwardly into engagement with the uppermost sheet on the stack so that an air flow through the orifices causes the upper sheets to be separated. After the vacuum fingers move upwardly and separate the upper sheet from the rest of the stack, the air supply tubes and riffling fingers begin moving downwardly and engage the top of the stack to hold it as the top sheet is fed into a paper transport device, such as a pair of rollers. A difficulty which may be encountered with this device is that since the air for riffling the sheets is supplied at constant volume and pressure, two or more sheets may tend to stick together and not be separated as intended resulting in paper jamming or feeding of multiple sheets of paper.

SUMMARY OF THE INVENTION In accordance with the present invention, means is provided for riffling the leading edge of a stack of sheets so that the sheets can be fed seriatim from the top of the stack by pickoff means, such as one or more vacuum fingers. This is accomplished by directing a stream of air through one or more variable orifices during reciprocal movement of one or more riffling fingers and during movement of the pickotf means. When the riffling fingers move out of sheet-gripping engagement with the top of the stack, air is directed against the leading edge of the stack at a high initial velocity and low initial volume. As the riffling fingers begin to move to a position spaced from the stack the high-velocity airstream separates the uppermost sheets. The riffling fingers continue to move away from the stack causing the air velocity to gradually decrease until a relatively high-volume low-velocity stream of air is provided to maintain the upper sheets of the stack in separated condition so that the uppermost sheet can be separated from the stack by a pickoff means, such as vacuum fingers.

More particularly, the invention contemplates a plurality of stationary air supply tubes adjacent to and extending upwardly from the forward edge of a support for a stack of paper. Air is supplied to the respective tubes near the lower end thereof and flows as a stream of air to a slot at the upper end of each tube. Each slot extends longitudinally along the respective tubes and faces the upper portion of a stack of paper. A riffling finger is mounted for reciprocal movement into and out of engagement with the top of the stack at each tube and each riffling finger includes a tab which extends through the slot into the tube to direct a stream of air through the slot and to vary the effective area of the slot through which the air can pass during the riffling operation. When the riffling finger is in a lower paper-engaging position the tab is positioned adjacent the bottom of the slot so that the air must pass through a highly restricted area. These high-velocity airstreams are effective to separate the uppermost sheets along the leading edges thereof. As the fingers move upwardly, the effective length of each slot is increased as the respective tabs move upwardly along the respective slots causing the airstreams to flow at a gradually decreasing velocity and gradually increasing volume. These high-volume airstreams hold the sheets in separated condition so that reciprocal vacuum fingers can separate the uppermost sheet from the stack. After separation, the riffling fingers move downwardly into clamping engagement with the top of the stack and the cycle begins again. This structure facilitates improved separation of sheets so that only one sheet is fed at a time and paper jams are largely eliminated. The riffling finger is operated by mechanical drive means in one embodiment and in another embodiment is pneumatically operated as a poppet valve by variable air pressure supplied through the tubes.

In a further embodiment, each riffling finger is mounted for reciprocal movement in a recess above a narrow vertical slot. When the finger is in engagement with the top of the stack, air passes through the slot as a restricted orifice at a relatively high velocity. However, when the riffling finger is raised air passes through both the slot and the portion of the recess below the riffling finger as a larger orifice at greater volume, but lower velocity.

Additional advantages of this invention will become apparent from the description which follows, taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. l is a top plan view of a sheet separator constructed in accordance with this invention for use with a sheet feeder;

FIG. 2 is an offset section, taken along line 2--2 of FIG. 1, showing the position of the riffling fingers of the sheet separator and the pickoff fingers of the sheet feeder at the beginning of a cycle;

FIG. 3 is a perspective view of one of the sheet separators of FIGS. I and 2;

FIG. 4 is a fragmentary section, similar to FIG. 2 showing the riffling finger in raised position;

FIG. 5 is a fragmentary section, similar to FIG. 4 showing the uppermost sheet being picked up by the pickoff finger as the riffling finger moves downwardly;

FIG. 6 is a fragmentary section similar to FIGS. 4 and 5 showing the uppermost sheet in feeding position and the riffling finger moving further downwardly;

FIG. 7 is a fragmentary section, similar to FIGS. 4-6 showing the uppermost sheet being fed from the pickoff finger while the riffling finger is in a lower sheet-gripping position;

FIG. 8 is a fragmentary section similar to FIG. 5 but showing an alternative embodiment wherein movement of the riffling finger is controlled by air pressure; and

FIG. 9 is a perspective, fragmentary view, similar to FIG. 3, but showing a further alternative embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with this invention .a sheet separator 2 is shown in FIG. I which operates in conjunction with sheet pickoff means, such as vacuum fingers 4, to feed sheets, such as paper from a stack 6, on sheet or paper support ll. Conveniently, support 8 is provided with a pair of adjustable side guides 10 and an adjustable end guide 12 movable along tracks 14 and 116, respectively, as shown and as more fully described in commonly assigned copending US application Ser. No. 29,403, entitled, Vacuum Paper Feeder," to Donald J. Albert filed Apr. 17, I970.

The sheet separator mechanism 2 includes a plurality of air supply tubes, such as tubes 18, fixedly mounted on and extending upwardly from the leading edge of sheet support 28. These tubes also serve as aligning means to position the leading edge of the sheets. Each tube has a central longitudinal slot 22, as best seen in FIG. 3 through which a stream of air is directed against the leading ends or edges of the sheets to separate them so that the vacuum fingers may pick up the up permost sheet to feed it to another station. As illustrated, air can be supplied to each of the tubes from a source (not shown) by means of hose 24, as best seen in FIGS. 1 and 2.

A riffling finger 26 is associated with each of the tubes 18 and includes a tab 27, extending through slot 22 for a purpose to be described, and a depending leg 28 which is illustrated as having a pair of vertically spaced slots 30 for reciprocal movement on spaced pins 32 extending from tube 18. To facilitate this reciprocal movement, an angle bracket 34 is attached to each leg 28 and includes an outstanding leg having a slot 36. A rod or bar 38 extends transversely through the respective slots, as best seen in FIGS. 1 and 2. This bar is supported on one end of a pair of spaced bellcranks 40 for essentially vertical reciprocal movement upon rotation of bell crank 40 with shaft 42 journaled in bearings 44 on support 20, as shown. The other end of each bellcrank 40 is connected by a shaft 45 to drive means 46 for counterrotationof the bellcrank to raise and lower riffling fingers 26 as described in further detail below.

The operation of sheet separator mechanism 2 can best be understood by looking at FIGS. 2 and 4-7. At the beginning of a cycle, during which the uppermost sheet on the stack is to be fed, the riffling fingers 26 are in a lowered sheet gripping or engaging position shown in FIG. 2. Each tab 27 restricts the flow of air to the lowermost portion of the respective slots 22. Thus airstreams are directed against the leading edges of the uppermost sheets at a high velocity to separate them as riffling fingers begin to move upwardly. This upward movement begins as vacuum fingers 4 are being lowered into engagement with the uppermost sheet of stack 6. The riffling fingers 26 are moved upwardly from the position shown in FIG. 2 to the spaced position shown in FIG. 4 upon counterclockwise rotation of bellcrank 40, as viewed in the drawings. As each riffling finger begins its upward movement, the tabs 27 increase the effective area of slots 22 resulting in an increase in volume and a decrease in the velocity of the airstream passing through the slots to hold the edges of the uppermost sheets in a separated condition, as shown. As vacuum fingers 4 move upwardly the uppermost sheet 48 will be separated from the stack with the leading edge being pulled past riffling finger 26 which is now moving in a downward direction to clamp the upper sheets against the rest of the stack, as in FIG. 5. In the position shown in FIG. 6 sheet 48 is ready for feeding and vacuum finger 26 has nearly returned to its lowered position. In FIG. 7 sheet 48 is being pulled away from vacuum finger 4 by paper feed means (not shown) as riffling finger 26 is again in its lowermost position engaging the uppermost sheet of paper. Of course, the cycle will be repeated each time a sheet of paper is to be fed.

An alternative sheet separator is shown in FIG. 8 wherein a stack of paper 6' is supported on a paper support 8' adjacent a tube 50. Poppet valve 52 is provided in the top of tube 50 and includes a tubular section or sleeve 54 which extends into the upper end of tube 50 and is constructed for a limited vertical movement as by providing a slot 56 in section 54 which is engaged by a pin 58 formed in tube 50. The upper end of section 54 is provided with a slot 60 just below a riffling finger 62 to direct a stream of air against the leading edges of the sheets. The flow of air to tube 50 is regulated by a solenoid valve 64 in a supply line 66 connected to tube 50. Valve 64 can be regulated by control circuit 68 to provide a pulsating airflow to tube 50 to operate poppet valve 52. It can be seen that when riffling finger 62 is in a lowered position slot 60 is substantially within the upper end of tube 50. The poppet is in this position when little or no air is supplied to tube 50, as when solenoid valve 64 is closed by a control circuit 68. When the valve is opened, air is supplied to tube 50 which urges the poppet valve to the raised position shown so that air can pass through slot 60. At the beginning of the upward movement of the poppet valve, only a small portion of slot 60 extends above tube 50 so that the issuing airstream has a high velocity and a low volume to separate the uppermost sheets. Then, as the poppet valve moves further upward toward its uppermost position, the exposed portion of slot 60 becomes increasingly greater so that the airstream has a high volume and low velocity to maintain the separated sheets in that condition so that the uppermost sheet 48' may be fed as by a pickoff finger 4'.

A further alternative embodiment is disclosed in FIG. 9 wherein a riffling finger 70 is formed as an insert in a top plate 72 extending forwardly from a vertically reciprocal leg 74. Leg 74 is illustrated as having a pair of outstanding arms 76 and 78 which are adapted to be engaged by reciprocal drive means (not shown) to move riffling finger 70 up and down in recess 80 of stationary tube 82. Adjacent the upper end of tube 82 and extending downwardly from the center of recess 80 is a longitudinal slot 84 through which air is directed from passageway 86 by curved surface 88 between spaced flanges 90 and 92. These flanges are formed integrally with leg 74, and are spaced apart a distance equal to the width of slot 84.

When the riffling finger is in the lower position, the air is directed from passageway 86 through slot 84 at a relatively high velocity to separate the sheets as the riffling finger begins to move upwardly. As the riffling finger moves up to the position shown in dotted lines, air is also permitted to flow through the portion of recess 80 below finger 70 thereby allowing a greater volume of air to flow at a lower velocity to hold the uppermost sheets in separated condition. Thus, recess 80 serves to vary the effective size of slot 82.

From the foregoing, it can be seen that a sheet separator constructed in accordance with this invention will work in a highly efficient manner. At the beginning of a sheet-feeding cycle air is directed in streams and at a high velocity against the leading edges of the uppermost sheets of a stack to separate them from the rest of the stack. As the riffling fingers are raised the airstreams are directed against the sheets in ever increasing volume but at a lower velocity as the effective size of the orifice through which the airstream passes becomes greater. Advantageously, the variable airflow facilitates separating the sheets and maintaining them in separated condition until the uppermost sheet has been removed from the stack. After separation of a sheet from the stack, the riffling fingers move to the lowered position to clamp the rest of the sheets against the stack until the start of the next cycle. In one embodiment, the effective size of a slot through which the airstream is directed is changed by a tab extending from the riffling finger through the slot and moving up and down with the riffling finger. In a second embodiment, the riffling finger is in the form of a poppet valve and includes a slot whose effective area varies in accordance to the position of the poppet valve. These structures reduce the possibility of more than one sheet being fed from the stack at a time and hence reduces the possibility of paper jams.

The invention has been described in detail with reference to preferred embodiments thereof, but it will be understood that variations and modifications can be efi'ected within the spirit and scope of the invention.

I claim:

I. A sheet separator for separating leading edges of sheets and for feeding the sheets seriatim from the top of a stack, said separator comprising:

a support for positioning a stack of sheets to be fed;

sheet pickoff means movable into engagement with the uppermost sheet of said stack and movable away from said stack to separate said sheet from said stack and feed said sheet away from said stack;

variable orifice means spaced from said support for directing a stream of air against the leading edges of said sheets to separate them;

means for supplying the stream of air to said variable orifice means;

at least one movable riffiing finger mounted for movement between a stack-engaging position and a position spaced from said stack to vary the effective size of said variable orifice means to cause said airstream to be directed against said leading edges at high velocity and low volume when said finger is in said stack-engaging position to separate said sheets and to be directed at high volume and low velocity when said finger is in said spaced position to maintain said sheets in separated condition; and

means for moving said riffling finger in response to movement of said pickoff means.

2. A sheet separator as claimed in claim 1, further including:

means for aligning the leading edges of said sheets adjacent said variable orifice means so that said airstream will maintain the edges of the uppermost sheets separated so that said pickoff means can separate the uppermost sheet from said stack of the uppermost sheets separated so that pickoff means can separate the uppermost sheet from said staclc.

3. A sheet separator as claimed in claim 1, further including:

at least one air-supply tube fixedly attached to and extending from said sheet support; and

means adjacent an upper end of said tube defining said variable orifice means as including a longitudinal slot positioned for directing the airstream toward the leading edge of the stack.

4. A sheet separator as claimed in claim 3, wherein said movable means includes:

a tab extending from said rifi'ling finger through said slot, movable with said riffling finger to vary the efiective size of said slot which is in communication with said air supply means.

5. A sheet separator as claimed in claim 3, wherein said movable means includes:

a poppet valve in said upper end of said tube including said longitudinal slot and said riffling finger and being movable in response to said air stream to vary the effective size of said slot extending above said top of said tube.

6. A sheet separator for separating leading edges of sheets and for feeding the sheets seriatim from the top ofa stack, said separator comprising:

a support for positioning a stack ofsheets to be fed;

sheet pickoff means movable into engagement with the uppermost sheet of said stack and movable away from said stack to separate said sheet from said stack and feed said sheet away from said stack;

a plurality of stationary air supply tubes extending from said support to align the leading edges of said sheets, said tubes each having an end spaced from said support;

means for supplying a stream of air to each of said tubes;

means defining a longitudinal slot in each of said tubes for directing said stream of air against the leading edges of said sheets to separate them;

an oscillatible riffling finger mounted in each of said tubes for movement between a stack-engaging position and a position spaced from the uppermost sheet of said stack to vary the effective size of said respective slots to cause said airstreams to be directed against said leading edges at high velocity and low volume when each of said riffling; fingers is in said stackengaging position to separate said sheets and to be directed at high volume and low velocity when each of said riffling fingers is in said spaced position to maintain said sheets in separated condition; and

means for oscillating said rifiling fingers in response to movement of said pickoff means.

7. A sheet separator as claimed in claim 6, wherein said oscillating means includes:

mechanical means for moving said plate between said stackengaging position and said separated position.

8. A sheet separator as claimed in claim 6, wherein said oscillatible riffling finger is mounted on a sleeve extendable into said tube and reciprocal therein in response to air pressure supplied to said tube.

9. A sheet separator as claimed in claim 6, wherein said oscillating means includes: I

pivotal y mounted bell crank having a first and a second end;

means connecting said first end of said bellcrank to each of said riffling fingers; and

means connected to said second end of said bellcrank means for pivoting said bellcrank in a. first direction to move said riffling fingers to said spaced position when said pickoff means is brought into contact with the uppermost sheet and for pivoting said bellcrank in a second direction to move said riffling fingers to said stack-engaging position when said picltoff means is moved away from said stack.

10. A sheet separator as claimed in claim 6, further including:

means defining a recess in said end of each of said tubes, each said recess being in communication with one of said slots, said riffling fingers extending through said respective recesses so that when said fingers are spaced from said stack said airstreams flow through both said slots and said recesses thereby varying the effective size of said slots. 

1. A sheet separator for separating leading edges of sheets and for feeding the sheets seriatim from the top of a stack, said separator comprising: a support for positioning a stack of sheets to be fed; sheet pickoff means movable into engagement with the uppermost sheet of said stack and movable away from said stack to separate said sheet from said stack and feed said sheet away from said stack; variable orifice means spaced from said support for directing a stream of air against the leading edges of said sheets to separate them; means for supplying the stream of air to said variable orifice means; at least one movable riffling finger mounted for movement between a stack-engaging position and a position spaced from said stack to vary the effective size of said variable orifice means to cause said airstream to be directed against said leading edges at high velocity and low volume when said finger is in said stack-engaging position to separate said sheets and to be directed at high volume and low velocity when said finger is in said spaced position to maintain said sheets in separated condition; and means for moving said riffling finger in response to movement of said pickoff means.
 2. A sheet separator as claimed in claim 1, further including: means for aligning the leading edges of said sheets adjacent said variable orifice means so that said airstream will maintain the edges of the uppermost sheets separated so that said pickoff means can separate the uppermost sheet from said stack of the uppermost sheets separated so that pickoff means can separate the uppermost sheet from said stack.
 3. A sheet separator as claimed in claim 1, further including: at least one air-supply tube fixedly attached to and extending from said sheet support; and means adjacent an upper end of said tube defining said variable orifice means as including a longitudinal slot positioned for directing the airstream toward the leading edge of the stack.
 4. A sheet separator as claimed in claim 3, wherein said movable means includes: a tab extending from said riffling finger through said slot, movable with said riffling finger to vary the effective size of said slot which is in communication with said air supply means.
 5. A sheet separator as claimed in claim 3, wherein said movable means includes: a poppet valve in said upper end of said tube including said longitudinal slot and said riffling finger and being movable in response to said air stream to vary the effective size of said slot extending above said top of said tube.
 6. A sheet separator for separating leading edges of sheets and for feeding the sheets seriatim from the top of a stack, said separator comprising: a support for positioning a stack of sheets to be fed; sheet pickoff means movable into engagement with the uppermost sheet of said stack and movable away from said stack to separate said sheet from said stack and feed said sheet away from said stack; a plurality of stationary air supply tubes extending from said support to align the leading edges of said sheets, said tubes each having an end spaced from said support; means for supplying a stream of air to each of said tubes; means defining a longitudinal slot in each of said tubes for directing said stream of air against the leading edges of said sheets to separate them; an oscillatible riffling finger mounted in each of said tubes for movement between a stack-engaging position and a position spaced from the uppermost sheet of said stack to vary the effective size of said respective slots to cause said airstreams to be directed against said leading edges at high velocity and low volume when each of said riffling fingers is in said stack-engaging position to separate said sheets and to be directed at high volume and low velocity when each of said riffling fingers is in said spaced position to maintain said sheets in separated condition; and means for oscillating said riffling fingers in response to movement of said pickoff means.
 7. A sheet separator as claimed in claim 6, wherein said oscillating means includes: mechanical means for moving said plate between said stack-engaging position and said separated position.
 8. A sheet separator as claimed in claim 6, wherein said oscillatible riffling finger is mounted on a sleeve extendable into said tube and reciprocal therein in response to air pressure supplied to said tube.
 9. A sheet separator as claimed in claim 6, wherein said oscillating means includes: pivotally mounted bell crank having a first and a second end; means connecting said first end of said bellcrank to each of said riffling fingers; and means connected to said second end of said bellcrank means for pivoting said bellcrank in a first direction to move said riffling fingers to said spaced position when said pickoff means is brought into contact with the uppermost sheet and for pivoting said bellcrank in a second direction to move said riffling fingers to said stack-engaging position when said pickoff means is moved away from said stack.
 10. A sheet separator as claimed in claim 6, further including: means defining a recess in said end of each of said tubes, each said recess being in communication with one of said slots, said riffling fingers extending through said respective recesses so that when said fingers are spaced from said stack said airstreams flow through both said slots and said recesses thereby varying the effective size of said slots. 